Quasiclassical theory of charge transport across mesoscopic normal-metal–superconducting heterostructures with current conservation

Abstract

We consider the steady-state nonequilibrium behavior of mesoscopic superconducting wires connected to normal-metal reservoirs. Going beyond the diffusive limit, we utilize the quasiclassical theory and perform a self-consistent calculation that guarantees current conservation through the entire system. Going from the ballistic to the diffusive limit, we investigate several crucial phenomena such as charge imbalance, momentum-resolved nonequilbrium distributions, and the current-to-superflow conversion. Connecting to earlier results for the diffusive case, we find that superconductivity can break down at a critical bias voltage Vc. We find that Vc generally increases as the interface transparency is reduced, while the dependence on the mean-free path is nonmonotonous. We discuss the key differences of the ballistic and semiballistic regimes to the fully diffusive case.

Similar papers